As resistance change type elements for storing data using a change in resistance of elements, magnetic random access memories (MRAMs) have been developed. A current is caused to flow through magnetic tunnel junction (MTJ) elements to thereby write data into the MTJ elements.
One end of each MTJ element is connected to a corresponding first bit line via a corresponding selection transistor, and another end of each MTJ element is connected to a corresponding second bit line via a corresponding upper electrode. Each upper electrode is typically connected to a corresponding second bit line via a single via contact.
To cause a sufficient write current to flow through MTJ elements, a plurality of selection transistors may be provided to respectively correspond to the MTJ elements. In this case, a large current flows through via contacts between the upper electrodes and the second bit lines during data write operation. Each upper electrode is commonly connected to two MTJ elements neighboring in the word line direction in some cases. In such cases, the current flowing through the via contacts further increases.
If the current is concentrated on the via contacts, metal materials constituting the via contacts may deteriorate due to electromigration. The deterioration of the via contacts causes lowering of the reliability of a semiconductor memory device.